191 



täte the filtrate "with acetate of lead, treat the deposit with diluted 

 acetic acid, filter, heat the filtrate to boiling point and precipitate 

 with snbacetate of lead. Decompose the deposit under water with 

 sulphuret of hydrogen and evaporate the filtrate in a current of 

 carbonic acid gas. — Amber-yellow powder of an acidulous, acerb 

 taste, greens the salts of oxyd of iron, separates on heating with 

 diluted acids a red-yellow powder (]Ahodoxanthin=r2 C14 H7 0$ 

 + HO). 



Rhoea(lin=C42 H21 NO12. Peculiar alkaloid occurring in all 

 parts of Papaver Rhoeas and allied species. Treat the whole herb 

 with warm water, concentrate the extract, oversaturate with car- 

 bonate of soda and shake repeatedly with ether. Transfer the Rhoea- 

 dinfrom the ethereous solution to an aqueous solution of bitartarate 

 of soda by shaking, throw away the ether and precipitate the aqueous 

 liquid with ammonia, wash the deposit, dry, and boil with alcohol, 

 in oi'der to remove dyeing matters and an alkaloid which exists in 

 the plant in small quantity only, and seems to be thebain. The 

 Rhoeadin remains by this process for the greatest part undissolved. 

 To purify it completely, dissolve the remnant in acetic acid, shake 

 with animal charcoal and precipitate with ammonia. — Forms small, 

 white prisms, tasteless either by itself or in solution; fuses at 232° 

 without loss of weight, becomes brown and sublimates jmrtly; is 

 almost insoluble in ether (in 1280 parts), benzol, chloroform, 

 alcohol, water, liquor of ammonia, soda-ley and lime-water; the 

 alcoholic solution has a scarcely perceptible alkaline reaction. 

 Dissolves in acids, without being able to neutralise them or even 

 to remain in contact with them without alteration (to tuni red), 

 especially hydrochloric and sulj^huric acids, yielding purple-red 

 solutions. Alkalies restore the original colour. The red coloura- 

 tion is accompanied by the production of a colouring substance, 

 and of a new alkaloid of highly basic propeities and of the same 

 composition as Rhoeadin. Concentrated sulphuric and nitric 

 acids dissolve the Rhoeadin under decomposition, the former acid 

 with olive-green, the latter with yellow colour. The colourless 

 solution of Rh. is precipitable by tannin, chloride of mercury, etc. 



RllOitailllic Acid = C'ls H14 O13. In the leaves of Rhus 

 Toxicodendron. Shake the ethereous extract with warm water, 

 filter, allow to rest for two days, filter anew, throw do\vn sulphuric 

 and phosphoric acids l^y means of a little acetate of lead, filter 

 and precipitate completely with acetate of lead, decom]iose the 

 latter deposit under water with sulphuret of hydrogen ; filter and 

 evaporate. — Amorphous, yellowish-green, gum-like mass, of slightly 

 bitter taste and acidulous reaction, coloui's and precipitates the 

 salts of oxyd of iron dark green, colours tartarated antimony dark 

 yellow without precipitation, turbidifies solvitions of glue when 

 concentrated. 



